Thanks always for the help, John. I got it squared away.
I can't explain it all in the proper technical terms but the gist of it is this:
The camera is an Axis M3046. Our VMS is Lenel OnGuard, which doesn't have the M3046 written into it, so like I've done with dozens in the past, I input the camera as an Axis M3026 and it works just fine.
However, this is the first and only time we've ever had a monitor connected to the camera. I don't think the VMS liked having the camera in HDMI capture mode to facilitate the external monitor because the VMS automatically defaulted it to QHD capture mode, thereby rendering the monitor without an image.
After figuring this out I deleted the camera out of OnGuard, set the capture mode to HDMI, configured the SD card for recording, and now all is well.
Except for the 503 service issue. At the time of my post the camera was stand alone with only one client connected, which was the PC I was on to view the camera.
(Here comes the lack of technical jargon) Despite the fact that the camera was deleted from OnGuard, I think OnGuard still had "remnants" in the camera. I think the 503 Service issue was somehow the result of OnGuard's past control of the camera.
After I "Restored" all parameters, except the IP parameters, to the original factory settings, the 503 Service issue was TCO.
Does anyone have any thoughts on my "remnants" theory?